#include <bits/stdc++.h>
using namespace std;
int main()
{
    int n, x;
    int a[11234];
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    cin >> x;
    int ans = -1;
    for (int i = 1; i <= n; i++)
        if (a[i] == x)
        {
            ans = i;
            break;
        }
    cout << ans;
    return 0;
}